Technical Field
The present disclosure relates, generally, to the development of alternative coatings and methods for water and oil protection or repellants, to control and/or eliminate the effect of humidity and oily substances on various surfaces. These coatings, which are halogen-free, exhibit little to no toxicity to humans, non-human animals, including pets and other domesticated animals, and, therefore, may be safely employed for use on monuments, textiles, metals, stone, ceramic, wood, and other surfaces and when otherwise exposed to the environment.
Description of the Related Art
Coatings are usually applied for protecting surfaces from water, oil, and/or dirt. A variety of hydrophobic and oleophobic surface coating compositions have been described, must of them containing an halogen or derivative, which are normally used to produce very low surface energies and, thus, impinge the hydrophobic property on a surface, as in U.S. Pat. No. 6,663,941, which discloses hydrophobic coating compositions and processes for coating articles with such hydrophobic coating compositions. The authors claim there that durable, weatherable and scratch-resistant coatings are provided by compositions comprising a trifluoromethyl-containing component and a hardenable material. However, they also state that forming hydrophobic coatings on articles involves no substantial loss of fluorocarbon solvent used in the coating composition. As a result, their technology forms an exposed surface populated with 30% by area or more terminal trifluoromethyl groups. In other words, they strongly rely on both, hazardous solvents and fluorine-containing substances, which are known to be highly detrimental to the environment. Most patents and commercial products that claim hydrophobic and/or lipophobic properties, rely on fluorine or derivatives.
U.S. Pat. No. 5,476,717 describes a material having anti-reflective, hydrophobic, and abrasion-resistant properties. The '717 patent also relates to a process for depositing an anti-reflective, hydrophobic, and abrasion-resistant material on an organic or inorganic substrate. The material process described in the '717 patent requires the use of an adhesion-promoting coating, which permits the active reinforcement of the mixing of the anti-reflection coating to the substrate. The material described in the '717 patent is designed specifically for use with optical components, but not for large scale industrial applications, and requires use of a primer, which includes an adhesion promoter agent and requires pretreatment of the surface to be coated.
Attempts have been made to provide alternatives for reducing the surface energy of a coating, such as the halogen-free coatings that are described in PCT Patent Publication No. WO 1995/008515, which are made in aqueous solution by polymerizing an amino-oxysilane having at least one primary amine group to control pH and water solubility. The '515 PCT relates exclusively, however, to the formation of a high performance binder for use in inorganic protective coatings to enhance the coating's weather, heat, and chemical resistance and to provide a flat or glossy surface finish as well as a zinc rich composition that can be used exclusively as a component of a paint or coating formulation (i.e., as a binder), including epoxy, polyurethane, silicone, silicate, acrylic, vinyl, alkyd, chlorinated rubber, and the like. The '515 PCT further the polymerization in water of their components, which involves curing time and control of the reaction conditions.
U.S. Patent Publication No. 2003/0147932 described the physical nanostructuring of a coating composition, by forming a nanoemulsion, and the patterning of the surface to be protected to achieve a lotus-effect surface comprising a substrate having a surface and a plurality of irregularities associated with said surface wherein the lotus-effect surface comprises at least one anti-microbial material. The surface described in the '932 publication comprises particles having an irregular fine nanostructure, wherein the irregularities comprise a mixture of one or more types of hydrophobic particles and one or more types of anti-microbial particles. The '932 publication is, however, restricted to anti-microbial properties and does not contribute a hydrophobic or lipophobic behavior to the coated surface.